Statistical analysis on the incidence and predictors of death among second-line ART patients in public hospitals of North Wollo and Waghemira Zones, Ethiopia, 2021

Acquired immune deficiency virus, caused by the human immunodeficiency virus, is a significant global health concern. Sub-Saharan Africa particularly Ethiopia faces a high prevalence of human immunodeficiency virus. In low-income settings like Ethiopia, early mortality rates are elevated due to severe opportunistic infections and advanced disease at Anti-retroviral treatment initiation. Despite available treatments, delayed treatment initiation among Human Immunodeficiency Virus -infected individuals in Africa, including Ethiopia, leads to disease progression and increased mortality risk. This study aimed to identify the factors contributing to the death of HIV patients under treatment at second line regimen in public hospitals of North Wollo and Waghemira Zones. A retrospective cohort study with 474 patients was conducted in selected hospitals of North Wollo and Waghemira Zones. A parametric Weibull regression model was employed, and the adjusted hazard ratio served as the measure of association. Variables significantly affected the outcome of the study was determined at a p-value < 0.05, along with a 95% confidence interval for the variables. The patients were within the average age of 38.6(standard deviation ± 12.5) years and majority (45.57%) had no formal education. The overall death incidence rate among second-line anti-retroviral treatment patients was 1.98 per 100-person years [95% CI 1.4—2.9%]. Poor adherence to antiretroviral treatment, male gender, and being underweight significantly increased the hazard of death. Conversely, increased anti-retroviral treatment duration had a significant and negative impact, reducing the hazard of death among patients. The study reveals a high incidence of death among second line anti-retroviral treatment users. Independent predictors include poor adherence, male gender, and underweight status, all significantly increasing the risk of death. On the positive side, the hazard of death decreases with longer anti-retroviral treatment duration. A critical concern and counseling should be given for better ART adherence, to change their nutritional status and for males.


Sampling technique, inclusion and exclusion, sample size and data collection
This study was conducted based on secondary source data which was from patients medical records and charts.
A consecutive sampling method was applied and all HIV/AIDS patients who had followed up from September 2016 and April 2020 and who had minimum of 6 month on treatment of ART were included and incomplete charts were excluded.The patients who had followed up in the specified period was our study population.A total of 474 HIV/AIDS patients were used for this study.
Data extraction checklist was prepared based on literatures.An initial preliminary review was conducted to modify the extraction tool.

Variables of the study
The outcome variable of this study was time from second -line ART initiation to death.

Event
The event of interest for this study is the death of HIV/AIDS patients in second line ART treatment.

Censored
This study include those patients who are lost to follow up, live beyond the study period and deaths unrelated to their diseases.

ART adherence
The level of ART drug adherence was classified as good if ≥ 95% adherence by pill count, fair if 85% to 94% adherence by pill count, or poor if < 85% adherence by pill count.

Data management and analysis
The collected data was entered by EpiData-3.3.1.The entered data was exported to Stata version 17 for further statistical analysis.According to the proportion of missing to be managed, missing data was managed by imputation method using R software.
Descriptive statistics was reported using text, table and graph.Specific to survival analysis, data were presented by Kaplan Meier survival curve.In this study survival analysis was done to identify predictors of incidence of death.Survival analysis is a statistical method used to analyze time-to-event data, where the event of interest is typically death, failure, or any other occurrence that marks the end of the observation period.In survival analysis, parameter estimation involves estimating the parameters of a survival model that describes the relationship between covariates and survival times.There are some commonly used parameter estimation methods for survival analysis.For parameter estimation, there are different survival models to be considered, these are semi-parametric (cox regression model) and parametric models (Exponential, Weibull, Gamma, Log normal,Loglogistic).The summary of formula of each parametric model is described as follows: The commonly used parametric distributions and parameters: Log-logistic where λ is the location parameter, p is shape parameter.In this study, proportional hazard assumption was checked using graph, global tests and adding time varying covariates.
Model fitness was checked using AIC and a model with lower AIC value was selected as the best fitted model.Bi-variable analysis was done and variables with p-value less than 0.25 were entered into multivariable analysis.Finally to assess the association of incidence of death and its predictors among second line ART patients, a parametric weibull regression model was done.A measure of association using Adjusted hazard ratio (AHR) was used and the variable significantly affected the variable of the study was determined at a p-value < 0.05, along with a 95% confidence interval for the variables.

Ethics approval and consent to participate
To conduct the study, ethical approval was obtained from Woldia University institutional review board (WDUIRB).Since the study was secondary data and which was not directly obtained from patients, permission letter to access the charts and records was given for selected hospitals of North Wollo and Waghemira zone.

Result Socio-demographic characteristics of participants
Regarding their demographic status, almost half 238(50.21%) of HIV/AIDS patients were in the age group 41 and above years old.Majority had no formal education (45.57%) and few (18.35%) were attended secondary and above education.Males were the dominant HIV/AIDS patients on second-line ART in this study which accounts 54.85%.Near to half of the patients were married (46.2%) (Table1).

Kaplan-Meier estimates
The Kaplan-Maier curve provides a useful summary of survival data and can be used to estimate median survival time.The curve showed that the data had no median survival time.This indicated that the number of censored is greater than event of interest (Fig. 1).

Incidence of death
There were 29 deaths and the person time of death was 1461.5 years.The overall incidence rate of death among second line ART patients were 1.98 [95% CI of 1.4 & 2.9%] per 100-person year.

Factors associated with incidence of death
Initially cox proportional hazard assumptions were assessed.The graph showed that the assumption was violated.
In order to confirm the violation of the assumption, a global test was used (phtest) and indicated that there was enough evidence to reject the hypothesis of proportional hazard assumption at p-value less than 0.05 (Global  www.nature.com/scientificreports/test p-value = 0.049).In addition, the information criteria support that the proportional hazard model was not the best fitted model.Therefore, parametric models were considered such as exponential, Weibull, Log normal, Log logistic and Gompertz.The best fitted model was parametric Weibull model and selected using information criteria such as log likelihood ratio test, AIC and BIC (Table 3).Lastly, multivariable Weibull regression model was used to assess the predictors of death.In multivariable Weibull regression, ART adherence, ART duration and BMI were significantly associated with incidence of death among second line ART patients.Patients who had poor ART adherence were 3.59 times more hazard of death as compared to those with good adherence [AHR = 3.59, 95% 1.39,9.24].Sex of patients was significantly associated incidence of death, being male increased the hazard of death by 2.36 times as compared to males [AHR = 2.36, 95% CI 1.06, 5.29].Regarding duration of ART, increasing the duration of ART by one year decreases the hazard of death by 0.97 times [AHR = 0.97, 95% CI 0.96, 0.98].Patients who are underweight had more hazard of death by 3.12 times as compared with those normal BMI [AHR = 3.12, 95% CI 1.37, 7.12] (Table 4).

Discussion
This study was aimed to identify the predictors of incidence of death among second line ART patients.Around two present of patients were died during their second line ART follow up.This finding was lower than a study finding of Tanzania, Dessie, Metema, Amhara region, Gofa Zone of SNNPs, Aksum 4,10,12,13,21,22 .This study was in lined with a study conducted in Harari hospital Ethiopia 16 .This study finding was also below the study result of Nekemte, Gondar and Debre Markos Comprehensive Specialized Hospital [23][24][25] .The possible variation might be the difference in study sample size or denominator and the characteristics of study participants in relation to socio demographic, socio economic and cultural variations.
Regarding predictors, those patients who had poor ART adherence were significantly and positively associated with the risk of death.This is in line with a study conducted in selected hospitals of Amhara region and Dessie referral hospital 12,21 .Other studies also support this finding like studies conducted in Harar, Africa and Asia point out that HIV-infected patients with poor ART adherence had a higher risk of death as compared to those who had good ART adherence 16,19 .Similarly a study conducted in West Amhara, Gofa zone of SNNPs, Tanzania and Sub-Saharan African Sites showed that poor ART adherence had the highest risk of death than adherent patients 2,22,26,27 .Study conducted in Nekemte showed that poor ART adherence was found to be an  www.nature.com/scientificreports/independent predictor of death 25 .However, in contrary to the study finding conducted at Gondar that fair adherence level had high hazard of death 23 .The reason might be because poor adherence leads to low levels of drug, driving to viral replication, drug resistance, and viral rebound.That in turn causes low CD4 count which leads to morbidity and death 28 .
Being male also significant predictor and increased the incidence of death of HIV/AIDS patients on second line ART.This finding is in line with the study conducted in Uganada, Iran and Zambia [29][30][31] .However this is in contrast with the study finding of Tennessee 32 .Other study conducted in China and Nepal showed that men have a significantly higher risk of death than female 33,34 .There is no scientific evidence on the mechanism how males are more prone to risk of death than females.But different studies point out possible reasons for their death as males have less health care access than female might be due to high workloads.Males delay in treatment adherence and may not have better recovery of immune system as compared to females 35,36 .
Increasing ART duration by one year reduced the risk of incidence of death during their follow up.This finding is comparable with the study conducted in southern India 37 .This is also supported by the study conducted in Debre Tabor and Southern Oromiyaa region indicated that the death rate of patients in the earlier months of ART initiation was high and it declined in the later months of follow-up 20,38 .The study conducted in Korea and Nepal showed that the risk of death was lower in late ART follow up (1-5 years later) than the first year of ART duration which is similar to this study finding 34,39 .The explanation could be that with a longer duration of antiretroviral therapy (ART), there is a potential for an increase in CD4 count, improved viral suppression, and a reduced likelihood of co-infection compared to the early stages of ART initiation.In the initial phases of ART, there might not be significant improvements in patient immunity, making them more susceptible to infections.However, as the duration of ART progresses, these factors may diminish, leading to a lower risk of death.
Nutritional status is the other key significant predictor that those patients who are underweight face the risk of death as compared to those normal BMI range.This finding was supported by the study conducted in Metema, Tanzania, East Africa and Nigeria, Sub-Saharan African Sites and found that being underweight patents were at high risk of death 8,13,26,40 .Being underweight increases the likelihood of negative clinical results and serves as a predictor for the development of opportunistic infections (OIs) in individuals with HIV/AIDS, ultimately leading to death 41 .

Conclusion
The incidence of death among HIV/AIDS patients on second line ART was high.The risk of death was significant among patients with poor adherence and those who are male and underweight.However, the hazard of death decreased as the duration of ART increased.Therefore, a critical concern and counseling should be given for better ART adherence, to change their nutritional status and for males.

Strengths and limitations of the study
As compared to cross-sectional survey, this study has strengths related to the design.This study was conducted by retrospective cohort design.Therefore, temporal relationships can be determined for the outcome variable and its predictors.Even though this study had strengths,there was limitations related to the source which was secondary nature of the data.Since the data was from patient records and charts, some important variables were not available. https://doi.org/10.1038/s41598-024-60119-1

Figure 1 .
Figure 1.Cumulative hazard of death of second line ART patients in North Wollo and Waghemira zone public hospitals.

Table 1 .
Socio-demographic characteristics of HIV/AIDS patients on second-line ART in North Wollo and Waghimra zone public hospitals.

Table 2 .
HIV related and other clinical important variables of HIV/AIDS patients on second-line ART in North Wollo and Waghemira zone public hospitals.

Table 3 .
Model comparison for selection of the best fitted model.LLR logliklihood ratio, AIC Akake information criteria, BIC Bayesian information criteria.

Table 4 .
Predictors of death of HIV patients under treatment at second-line regimen in North Wollo and Waghemira zone public hospitals.Significant values are in bold.CHR crude hazard ratio, AHR Adjust hazard ratio, CI Confidence interval, 1 reference.*p -value < 0.05.